Discernible patterns on a floor are sometimes desired for both aesthetic and functional reasons. As examples of functional reasons, discernible floor patterns can define walking paths to direct people to particular parts of a room or building, including to emergency exits. Relatively large squares, rectangles, circles and other shapes smaller than an entire room can establish intended locations on the floor of tables, chairs or other furniture or equipment or a gathering place, such as a reading group location on a classroom floor.
Large discernible patterns on a floor are also aesthetically desirable and can provide desired visual impressions, such as (a) greater or small size or room division, (b) visual organization from regimented pattern elements or (c) visual disorganization from design elements placed without discernible organization. Hospitality flooring installations often include borders and bold designs, resulting in demand for such discernible patterns in this segment of the flooring market.
U.S. Pat. No. 8,141,505 to Hall et al. (“Hall”), the entirety of which is incorporated herein by reference, describes a tufting machine and related system for controlling the machine to form “free-flowing patterns.” Hall discloses a needle bar with a plurality of needles arranged across the bar. A yarn is associated with each needle. A backing material is fed under the needle bar, which is reciprocated to drive the needles through and out of the backing material to form loops of yarn in the backing material.
If the needle bar did not move laterally relative to the backing and operated as described above, the resulting product would simply consist of yarn loops extending in lines of a single color along the length of the backing material. To form a pattern with the yarn loops, it is necessary for the needle bar to shift laterally to vary the positioning of the different color yarn loops on the backing material to form a design. Hall teaches a control system that is programmed with the desired pattern information and that controls operation of the machine, including shifting of the needle bar, to create a desired pattern in the final tufted product.
Hall teaches thread-up of the needle bar with a repeating pattern of yarn colors across the needle bar. Thus, if the desired product is to have three different yarn colors (A, B, and C), those three colors would be threaded-up in the same order or sequence across the entire needle bar (i.e., ABCABCABC, etc.). Hall teaches this same thread-up methodology of a repeating sequence or pattern of the colors regardless of the number of different color yarns desired to be used. The control system must be told how many different color yarns are being used so that it can adjust the shifting of the needle bar and speed of tufting accordingly, as discussed below.
The appearance of a yarn loop on the face of a tufted product can be controlled by controlling the height of that yarn loop. Where a yarn loop of a particular color, texture or other characteristic is not to be readily visible at a particular location, that yarn loop is formed or tufted “low” in that location so that the surrounding tufted loops of a different color or other characteristic that are to be visible are higher and thus more clearly visible.
Hall controls the visibility of yarn loops on a tufted product by controlling the tension placed on the yarn to either “pull low or backrob” a yarn loop. According to applicants' understanding, to “pull low” the yarn loop is first tufted to a tuft height and then partially pulled back through the backing material so as to form a lower height yarn loop extending from the backing material. To “backrob,” the yarn loop is first tufted and then pulled entirely from the face of the backing material. Some such loops are pulled entirely free of the backing, but others are left sufficiently embedded in the backing to “tack” the yarn in place on the backside of the backing. In this way, the backrobbed yarn loops are not visible at all on the face side of the backing material.
The implementation of pulling low or backrobbing results in a tufted product having a smaller amount of visible yarn on its face. To compensate for this, Hall teaches that the density of the yarn loops provided within a given length of the backing material must be increased. To achieve this, the machine must be operated at an increased or denser “stitch rate” (which Hall defines as the number of stitches per inch). Operation of the machine at a denser stitch rate slows the speed at which tufted fabric can be produced. For a given tufting bar reciprocation rate, the denser the stitch rate required, the slower the backing material can be fed through and tufted by the machine, and thus the slower the machine can be run.